The present invention relates to a motor-vehicle latch system. More particularly this invention concerns such a system which has actuators in the latch and a central controller for power opening any of the latches.
In a standard motor-vehicle central-lock system all of the door latches, even any latches of the trunk or gas-filler cover, are operated by a central controller and can each be moved between a latched position holding the respective door or lid closed and an unlatched position allowing it to open. Each passenger or driver door latch also normally has an outside operating handle and can also be moved between an unlocked position in which actuation of the respective outside handle shifts the latch into the unlatched position and a locked position in which actuation of the outside handle does nothing. Furthermore each latch normally comprises a fork engageable around a bolt extending from the door post, a pawl that can retain the fork in a position engaged around the door bolt and that can release the fork to allow the door to open. This fork/pawl structure is operated through a main locking lever shiftable between the above-described locked and unlocked positions by means of a respective small electrical drive operated by the central controller.
The controller can in turn be triggered by an operator normally carried by the driver. In the most sophisticated keyless-entry systems, the driver simply carries a small transponder that communicates with the controller to unlock the latches as the driver approaches his or her vehicle. Similarly the operator could be a standard push-button remote or a smart card. It could even be a standard edge-bitted key.
As described in EP 0,896,113 of Hochart and Girard the drive of each latch can also directly or indirectly move the latch from the latched to the unlatched position. To this end a release lever has an edge that coacts with a pin on the fork-retaining pawl. Pivoting the release lever requires considerable torque, so the drive motor for the latch must be fairly powerful. This largely loses the advantage of the standard central-system latches where a relatively small motor is used to move between the locked and unlocked positions.
In U.S. Pat. No. 5,802,894 of Jahrsetz a central control system for the door latches of a motor vehicle has a central unit connected to the door latches via a control line and the door latches each have a first electrically-operable actuator and a second electrically-operable actuator together enabling the xe2x80x9coperatexe2x80x9d, xe2x80x9clocked and unlockedxe2x80x9d, xe2x80x9cantitheft mode on and offxe2x80x9d and xe2x80x9cchild-safety mode on and offxe2x80x9d operations. The door latches can be mechanically identical and can have a keeper pawl controlled both by the first actuator and an interior lever which is effective only when the second operator has displaced a lever from its ineffective position into an effective position.
These central lock systems which employ the drive in the latch to effect the unlatching movement have the considerable disadvantage that, if the vehicle power fails, the doors cannot be opened from inside or out unless they have, in addition to the motor-powered actuation, a complete mechanical linkage. The alternative to providing such a redundant mechanical linkage is a redundant power supply which is not normally considered a reasonable option.
It is therefore an object of the present invention to provide an improved door latch for a central motor-vehicle latch system.
Another object is the provision of such an improved door latch for a central motor-vehicle latch system which overcomes the above-given disadvantages, that is which is of relatively simple construction but which can be locked and unlocked and latched and unlatched both by an individual mechanical linkage and an individual motor drive.
The invention is aimed at producing such a lock which, in spite of parallel powered and mechanical systems, is of simple and inexpensive construction.
A door latch for a motor-vehicle central-latch system having a central electronic controller and an operator for the controller latch has according to the invention a housing, a locking element displaceable on the housing between a position holding a door bolt and a position releasing the door bolt, and a pawl displaceable on the housing between a retaining position holding the locking element in its bolt-holding position and a freeing position allowing the locking element to assume its bolt-releasing position. A release lever pivotal on the housing into an actuated position can put the pawl into the freeing position and an outside operating lever is pivotal on the housing between actuated and unactuated positions. A main locking lever is pivotal on the housing between locked and unlocked positions. An electric motor in the housing can displace the main locking lever between its locked and unlocked positions. A link engageable between the main locking lever, the outside operating lever, and the release lever serves for, when the main locking lever is in the unlocked position and the outside operating lever is in its unactuated position, coupling the outside operating lever to the release lever to displace same into its freeing position on movement of the outside operating lever into its actuated position. When the main locking lever is in the locked position and the outside operating lever is in its actuated position, the link displaces the release lever into its freeing position on movement of the main locking lever into its unlocked position. Normally the link, when the main locking lever holds in the locked position, decouples the outside locking lever from the release lever.
Thus with this system the drive motor can function, as is standard, to switch the latch between its locked and unlocked conditions. In the locked position actuation of the outside operating handle is not transmitted to the release lever by the link. According to the invention, however, if the drive motor attempts to move the locking lever into the unlocked position while the outside operating lever is actuated, the locking lever is effectively coupled to or acts on the release lever to trip it and unlatch the latch. Thus the same drive motor can serve both to lock and unlock the latch and to unlatch it. It is not necessary to provide a second drive motor for the unlatching function.
The drive in accordance with the invention includes a worm mounted on the drive motor, a worm wheel meshing with the worm, and an eccentric on the worm wheel engageable with the main locking lever. The main locking lever has a forked end formed with a recess in which the eccentric is engageable. Of course the release lever can also be actuated directly by means of an inside door handle, and the main locking lever can also be directly actuated by means of an inside lock button or the like.
The main locking lever and release lever are formed according to the invention with crossing slots and the link is engaged in both of the slots. More particularly the link is a pin engaged through both of the slots and provided with a retaining disk between the main locking and release levers. Alternately as shown in above-cited U.S. Pat. No. 5,802,894, the link can be a lever pivoted on the latch.
The outside operating lever is pivotal on the housing about an axis parallel to axes of rotation of the main locking and release levers. In addition the outside operating lever has an angled cam edge engageable with the link in the actuated position of the outside operating lever on movement of the main locking lever from the locked position to the unlocked position. Thus as the link pin is moved by the main locking lever while engaged in the slot of the release lever, it is cammed to the side to actuate the release lever. The travel along the cam edge can be relatively long for considerable mechanical advantage so a relatively weak drive motor can be used.